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03 November 2003 AGE-NC Project No. 03-1055 Page 2 of 6 The estimated depth to ground water at the property is approximately 10 feet below surface grade (bsg),based on the map titled Lines of Equal Depth to Groundwater Spring 1996 published by the San Joaquin County Flood Control District and Water Conservation District(FCD&WCD). Based upon a previous investigation performed by AGE,ground water depth at the site ranges between 10 and 12 feet bsg. It is inferred from the map titled Lines of Equal Elevation of Groundwater Spring 1996, also published by the FCD&WCD, that ground water flows toward the northwest in the general area of the site, but this may be modified by changing recharge and discharge patterns. Ground water is considered to be of beneficial use and is used for domestic, industrial and commercial purposes. 2.2. UNDERGROUND STORAGE TANK REMOVAL A UST gasoline system reportedly operated on the site for approximately thirty years from 1940 until 1970. The UST system is assumed to have been removed after 1970, however, no records of the UST removal are available with the Tracy Fire Department, Tracy Building Department or the SJCEHD. 2.3. PREVIOUS SUBSURFACE INVESTIGATION On 04 May 2000, five soil probe borings were advanced at the site under observation by a representative of the SJCEHD. The probe borings were advanced in the former USTs excavation and the southern and central dispenser islands and two locations which are in the assumed hydrogeologic down-gradient location.All borings were advanced to depths of 20 feet bsg.A`grab' ground water was collected and analyzed from each soil boring. TPH-g was detected in soil samples in the former dispensers area and to a lesser degree in the former UST excavation. The depth limits of hydrocarbon-impacted soil was approximately 15 feet bsg and above 20 feet bsg. Table 1 summarizes the analytical data of the soil sample analyzed. TPH-g was detected in all grab ground water samples at concentrations ranging from 370 gg/l in sample B 1-1120 to 55,000µg/1 in sample 113-1120.Excluding sample 135-1120,benzene was detected in the remaining samples at concentrations ranging from 0.54 µg/1 in sample B 1-1120 to 160 µg/1 in sample 133-1120. Toluene was detected in all five ground water samples at concentrations ranging from 11 to 25 µg/1. Ethylbenzene was detected in sample B3-H20 at 58 µg/1 and sample 134-1120 at 2.5 µg/1.Xylenes were only detected in samples B2-H2O,133-1120 and 134-1120 at concentrations of 230 µg/1, 120 µg/1 and 1.9 µg/1, respectively. MTBE was not detected in any of the ground water samples. In addition, the remaining fuel oxygenates were not detected in sample B3-1120. Advanced GeoEnvironmen[al,Inc.